Thymosin Alpha-1 is a biologically active peptide derived from prothymosin-alpha. Current hypotheses consider Thymosin Alpha-1 to be the main constituent of Thymosin Fraction-5, and as such it is considered to be the active component that restores the immune function in both athymic animals and animals with dysfunctional thymus glands. Thymosin Alpha-1 was among the first peptide isolates of Thymosin Fraction-5 to be sequenced and thereafter synthetically synthesized.
In humans, the PTMA gene encodes prothymosin-alpha, a 113 amino-acid polypeptide. Thymosin Alpha-1 is a 28 amino-acid fragment of prothymosin-alpha, and research has shown that this fragment derivative enhances the cell-mediated immune component of the human immune system. Its immune actions have enabled it to be used for treating viral infections such as Hepatitis B and Hepatitis C. It has also been incorporated into vaccines as an immune booster. Clinical studies have also shown that Thymosin Alpha-1 can be used to manage neoplasias since they upregulate cytotoxic T-cells which are involved in immune surveillance.